Use llvm::lower_bound. NFC

This reapplies rL358161. That commit inadvertently reverted an exegesis file to an old version.

llvm-svn: 358246
diff --git a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
index dc7ba93..290d592 100644
--- a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
@@ -535,8 +535,7 @@
   uint64_t Offset = getOffsetFromIndices(U, *DL);
   ArrayRef<unsigned> SrcRegs = getOrCreateVRegs(*Src);
   ArrayRef<uint64_t> Offsets = *VMap.getOffsets(*Src);
-  unsigned Idx = std::lower_bound(Offsets.begin(), Offsets.end(), Offset) -
-                 Offsets.begin();
+  unsigned Idx = llvm::lower_bound(Offsets, Offset) - Offsets.begin();
   auto &DstRegs = allocateVRegs(U);
 
   for (unsigned i = 0; i < DstRegs.size(); ++i)